Hi, I've got a fair bit of those APEC lights from the harbour bridge and im wanting to install them in my wagon

I got told they only run on 240V house

Im wondering what would happen if i hooked them up to my car battery with a switch on my dash board.

They wont work.

Your putting 240V lights on a 12v source

Id say those lights will be 500w or higher too. They will get very hot and need a decent sized inverter to run them, adequate cooling area, and hi current wiring as well. Also probably dangerous playing with 240v stuff on a car.

I think you should do it properly and get the right 12v lights